The present invention relates to novel modified or derivatized recombinant animal somatotropins wherein at least one (1) of the four (4) cysteine amino acids residues of said recombinant animal somatotropins is replaced, modified, deleted or derivatized. Although somatotropins have been and continue to be recombinantly produced, oftentime those somatotropins are difficult to formulate in order to effectively administer to an animal. Unlike such expressed somatotropins, it has been discovered that the alteration or elimination of the cysteine residues, four of which exist in somatotropins, either by substitution by another amino acid or by derivatization of the cysteines, results in biologically active compounds with enhanced stability to formulate in acceptable fashions in order to administer to animals.
It is the object of the present invention, therefore, to provide novel animal somatotropins wherein at least one (1) of the cysteine residues of the somatotropin has been replaced by another amino acid, modified, deleted or chemical derivatized. It is a further object of the invention to substitute and/or derivatize two (2), three (3) or all four (4) of the cysteine residues of animal somatotropins and provide those novel compounds. Two cysteines are in the small loop and two are in the large loop.
Also, another object of the present invention is to provide compositions of said substituted, replaced (modified), eliminated and/or derivatized animal somatotropins which are biologically effective and yet stable to administer. It is another object of the present invention to provide compositions of biologically active recombinant animal somatotropins which are suitable for parenteral administration comprising a growth promoting amount of a modified or derivatized recombinant animal somatotropin or pharmaceutically and pharmacologically acceptable salt thereof in a pharmaceutically and pharmacologically acceptable solid or liquid carrier, wherein the growth rate of an animal is increased over an extended period of time of five days or more.
These and other objects of the invention will become apparent by the more detailed description of the invention provided hereinbelow.